Ichiro Kondo
Department of Anesthesiology, Jikei University School of Medicine, 3-25-8,
Nishi-Shinbashi, Minato-ku, Tokyo 105-8461, Japan
Abstract: I investigated the role of protein kinaseﾊC (PKC) in
regulation of the capacitative Ca2+ entry and steroidogenesis
in bovine adrenocortical (BA) cells. Thapsigargin (TG)-treatment depleted
intracellular Ca2+ stores followed by induction of Ca2+
influx from the extracellular pool and also increasing of Mn2+
influx as an indicator of divalent cation influx in BA cells. CalphostinﾊC,
a PKC inhibitor, inhibited the TG-induced [Ca2+]i
elevation dose-dependently (0.1-1ﾊmM) and attenuated
Mn2+ entry. Phorbol 12-myristate 13-acetate (PMA), an activator
of PKC, potentiated the elevation of [Ca2+]i and enhanced
Mn2+ entry by TG treatment. These results suggest that PKC may
modulate capacitative Ca2+ entry in BA cells. In the presence
of extracellular Ca2+, TG enhanced cortisol production in BA
cells. CalphostinﾊC attenuated the TG-induced steroidogenesis dose-dependently
(0.25-1ﾊmM). PMA enhanced the steroidogenesis
dose-dependently (1-100ﾊnM). These results suggested that PKC may have a
modulatory effect on the capacitative Ca2+ entry that links to
steroidogenesis in BA cells.
Keywords: Capacitative Ca2+ entry, Protein kinaseﾊC, Adrenocortical
cell